An estimated six million colonoscopies are performed annually in the United States, predominantly as a screening procedure to prevent colon cancer. Many patients report the most difficult aspect of the procedure is the preparation taken the day, night and morning before the procedure to evacuate stool and any other residue from the colon to allow for optimal visualization of the colon during the colonoscopic examination. The several existing options for cleaning the colon involve a variety of means providing a large amount of fluid (i.e., whole bowel irrigation), both orally ingested as well as induced through secretions of the small bowel, to wash out bowel contents.
A widely used whole bowel irrigation liquid formulation includes polyethelene glycol (PEG) in solution with electrolytes. These are non-absorbed solutions that require the ingestion of a substantial amount of fluid. These PEG lavage preparations (e.g., GOLYTELY, NULYTELY, and HALF-LYTELY from Braintree Laboratories Inc. (Braintree, Mass.), and the fruit flavored COLYTE from Schwarz Pharma, Inc. (Mequon, Wis.), which are usually taken by the patient at home the night or evening before the examination, cleanse the bowel through the induction of diarrhea. The osmotic activity of polyethylene glycol, in combination with the electrolyte concentration, results in virtually no net absorption or excretion of ions or water. Accordingly, large volumes can be administered without significant changes in fluid and electrolyte balance. Individuals undergoing these whole bowel irrigation preparations complain of nausea and often vomiting because of the need to take in a large amount of (unpleasant) tasting fluid and significant hunger. While most patients understand the need to clear the bowel completely prior to an endoscopic procedure—adequate preparation is key to an accurate colonoscopy—many balk at these unpleasant whole bowel irrigation preps.